Established and emerging atmospheric pressure surface sampling/ionization techniques for mass spectrometry.

The number and type of atmospheric pressure techniques suitable for sampling analytes from surfaces, forming ions from these analytes, and subsequently transporting these ions into vacuum for interrogation by MS have rapidly expanded over the last several years. Moreover, the literature in this area is complicated by an explosion in acronyms for these techniques, many of which provide no information relating to the chemical or physical processes involved. In this tutorial article, we sort this vast array of techniques into relatively few categories on the basis of the approaches used for surface sampling and ionization. For each technique, we explain, as best known, many of the underlying principles of operation, describe representative applications, and in some cases, discuss needed research or advancements and attempt to forecast their future analytical utility.